1. Field of the Invention
The present invention relates to a single drive system for a bi-directional linear chemical mechanical polishing apparatus.
2. Description of the Related Art
U.S. Pat. No. 6,103,628, assigned to the assignee of the present invention, describes a reverse linear chemical mechanical polisher, also referred to as bi-directional linear chemical mechanical polisher, that operates to use a bi-directional linear motion to perform chemical mechanical polishing. In use, a rotating wafer carrier within a polishing region holds the wafer being polished.
U.S. patent application Ser. No. 09/684,059, filed Oct. 6, 2000, which is a continuation-in-part of U.S. Pat. No. 6,103,628, describes various features of a reverse linear chemical mechanical polisher, including incrementally moving the polishing pad that is disposed between supply and receive spools.
While the inventions described in the above patent and application are advantageous, further novel refinements to the drive system that creates the reverse linear (or bi-directional linear) motion have been developed, which are described herein.
The present invention offers many advantages, including the ability to efficiently produce reverse linear motion for a chemical mechanical polishing apparatus.
Another advantage of the present invention is to provide for the ability to efficiently produce bi-directional linear motion in a chemical mechanical polishing apparatus that also allows for the incremental movement of the polishing pad.
Another advantage of the present invention is the provision for a single casting that houses the polishing pad, including the supply spool, the receive spool, and pad path rollers.
The present invention provides the above advantages with a method and apparatus for producing bi-directional linear polishing that uses a flexible pad. In one aspect, a horizontal drive assembly moves a horizontal slide member that is horizontally moveable over rails attached to a single casting. Openings within the casting exist for the inclusion of the supply spool, the receive spool and the pad path rollers. A drive assembly translates the rotational movement of a motor into the horizontal bi-directional linear movement of the horizontal slide member. With the polishing pad properly locked in position, preferably being attached between the supply spool and the receive spool, horizontal bi-directional linear movement of the horizontal slide member creates a corresponding horizontal bi-directional linear movement of a portion of the polishing pad. Thus, the portion of the polishing pad disposed within a polishing area of the chemical mechanical polishing apparatus can polish a top front surface of a wafer using the bi-directional linear movement of the portion of the polishing pad.